ALSA: hda: support for wallclock timestamps

ALSA: hda: support for wallclock timestamps

Reuse code from clocksource to handle wall clock counter.
Since wrapparound occurs, the audio timestamp is reinitialized
to zero on a trigger. Synchronized linked devices will
start counting from same reference to avoid any drift.

Max buffer time is limited to 178 seconds to make sure
wall clock counter does not overflow

Wallclock timestamps are disabled on capture streams
until we figure out how to handle digital inputs.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>